Cobalt sulfate relative humidity indicators



Patented Jan. 25, 1 949 UNITED STATES ATENT OFFICE 2,460,065 coe'ALrSULFATE REL 'rrv'E nnmnrr'r INDICATORS I Paul Bell Davis, Baltimore,Md., assignor to The Davison Chemical Corporation, Baltimo'ra Md.

No'DraWing. Application February 7, 1945', Serial No. 576,716.

V 8 Claims. 1 This invention relates to indicators and more particularlyhas reference to compositions for indicating the presence and quantityof moisture in a gaseous atmosphere.

Many chemical compounds and especially a number of salts exist in theanhydrous and hy- In the manufacture of certain products control of thehumidity of the airor other gaseous atmosphere is important. Itsometimeshappens that even a fraction of a percent of relative humidity in anatmosphere may be detrimental to the operation of a process or theproduct resulting thereform.

An object of this invention is to indicate the presence of moisture in'a gaseous atmosphere at predetermined relative humidities or ranges ofrelative humidities.

Another object of this invention is to provide a moisture indicatorcapable of response to the moisture in gaseous atmospheres atpredetermined relative humidities.

A further object of this invention is to provide a moisture indicatorcomprising an adsorbent material having a color changing moistureindicating compound carried thereby.

Still another object of this invention is to provide a moistureindicator comprising an adsorbent material having a color changingmoisture indicating compound carried therebyin which the adsorbentcharacteristics of the carrier, its moisture content, the color-moisturecontent characteristics of the indicating compound and the concentrationthereof are correlated to respond to a predetermined relative humidityof a gaseous atmosphere in contact "therewith.

Yet another object of this invention is to provide a moisture indicatorcomprising a compound which is color responsive to changes in moisturecontent, carried by silica gel. 7

It is also an object of this invention to provide a method of' making amoisture indicator by depositing a color changing moisture indicatingcompound in theporesof a porous adsorbent and correlating the characterof the adsorbent, its

moisturebontnt, and the character and quan- 2 tity of th color changingcompound to obtain a color response to a predetermined relative humidityof a gaseous atmosphere in contact with the indicator.

With these and other objects in View the present invention resides inthe association of a compound, having one color in the anhydrous stateand a different color in the hydrated state, with an adsorbent such assilica gel and correlating the character of the adsorbent, its moisturecon tent and the character and content of the color changing compound.Thus by employing an adsorbent having determined adsorbent charac-'teristics and a determined moisture content as a carrier for a quantityof a predetermined compound exhibiting predetermined color changes withrelation to the quantity of water associated therewith, and by varyingthe quantity of the compound and the temperature to which the carrierand compound are heated, an indicator can be obtained which willrespond, by a change in color, to a predetermined relative humidity orrange or relative humidities of a gaseous atmosphere to which theindicator is exposed.

A number of compounds such as cobalt sulphate, cobalt bromide, cobaltphosphate, cobalt chloride, cobalt iodide, cobalt thiocyanate, cop'- perbromide, copper chloride, cobalt fluoro-silicate, and others, changecolor with changes in the amount of water associated therewith. Forexample, cobalt chloride in the anhydrous state is of a blue color butwhen associated with water the color changes. When cobalt chloride hastaken up its full water content, it has a pink color.

In accordance with the present invention it has been found that byassociating a compound,

which has one color in the anhydrous state anda different color whencombined with water, with an adsorbent, the so treated adsorbent may beemployed for indicating the relative humidity of an atmosphere to whichthe same is exposed.

For instance, by impregnating an adsorbent such as silica gel withasolution of cobalt chloride, and drying and activating the so treatedsilica gel, 2. product is obtained having a blue color. When the bluecolored silica gel is exposed to a humid atmosphere, moisture from theatmosphere is adsorbed by the silica gel and as the water content of thegel is increased the color of the gel gradually changes to pink. Thechange in color is due to water combining with the an= hydrous cobaltchloride in the pores of the gel. It has been discovered according tothe resent invention that by using a silica el having ce r= tainadsorptive characteristics, by incorporating a certain amount of cobaltchloride in the gel and by heating the treated gel to a certaintemperature, the thus treated gel will change color when exposed to anatmosphere having a relative humidity of a certain minimum value orrange of values. -It has also been discovered that by changing'one ormore of the factors, characteristics or conditions, the thus treated gelwill respond to a different minimum relative humidity value or range ofvalues. Apart from varying the factors, characteristics, conditions,etc., itv

EXAMPLE 1 SPECIMEN I-B Cobalt Sulphate (C0304) is highly useful inpracticing the present invention. For instance, standard silica gel madeby washing an acid reacting hydrogel with acidic wash water at about 150F., drying and then activating at about 850 Foand of a size of about6-16 mesh, has been treated with an aqueous solution of 00804 ofsufficient concentration and in a sufficient amount to incorporate inthe gel a deposit'of C0504 of about 2% of the total weight of the geland C0504 on a dry basis. After drying at a temperature of about 300 F.and activating at a temperature of about 475 F., the resulting producthad a dark purple color or more specifically a Munsell color value ofabout 5.0 P 4/12.

Upon exposing this product to an atmosphere havinga relative humiditybetween about fir- /z the color changed to a dark reddish purple atrelative humidity, then to a medium red purple at /g% relative humidity,or more specificaziiy to a color ranging between 7.5 P 4/8 and 5.0 RP6/10 M. C. V.

- EXAMPLE 2 SPECIMEN II-B By varying the temperatures at which the gelcontaining about 2% C0804 is dried and activated, a color change orbreakoccurred upon exposing the so treated gel to an atmosphere having adifierent relative humidity. For in-. stance, upon drying the gel atabout 300 F. and activating it at about 850 F. the color will changefrom 10.0 PB 3/10 Munsell color value to 10.0 P 5/8 M. C. V. whenexposed to an atmosphere having a relative humidity of about 3%. Uponexposure to an atmosphere having a relative humidity of about 5% thecolor "will change further to 5.0 RP 6/10 M. C. V.

EXAIVIPLE 3 SPECIMEN I1I-B posure to an atmosphere having a relativehumidity of about 5%; and upon further exposure to an atmosphere havinga relative humidity up to about 10% the color will change to 10.0 RP 6/10 M. C. V.

4: SPECIMEN II-A.

By treating the gel mentioned in Example 1 with a cobalt sulphatesolution so that the gel will contain about 2% cobalt sulphate, dryingsaid gel at a temperature of about 350 F. and activating the same at atemperature of about 725 able for indicating the moisture content of anatmosphere. having a relative humidity ranging between 1% and 3%. Forinstance, by exposing such a gel having Munsell color value of about10.0 PB 4/10 to anatmosphere, the relative humidity of which is about1%, the color will change to about 10.0 P 6/6 M. C(V. and for a relativehumidity of about 3% the color will change to about 7.5 RP 7/6 M. C. V.I

EXAMPLE 5 SPECIMEN LA 7 By treating the gel mentioned in Example 1 witha cobalt sulphate solution in a quantity calculated to produce a coloredgel containing about /2% cobalt sulphate, drying the so treated gel at250 F. and activating the same at about 525 R, an indicator gel willbeobtained which has a Munsell color value of about 5.0 P 6/4. Uponexposing this indicator gel to an atmosphere having a relative humidityof about 4% the color value will change to about7.5 RP 7/6 M. C. V. andupon exposing the same to an atmosphere having a relative humidity ofabout /2% the color will change to about 10.0 RP 7/6 M. C. V.

EXAMPLE 6 SPECIMEN IV--B treating a gel similar to that set forth inExample 1 but which had been washed with Water at a temperature of aboutR, dried and then activated at about 1200 13. and sized to 6-12 mesh,with a quantity of cobaltsulphate solution calculated to impregnate thegel with about 3% cobalt sulphate. Upon drying the so treated gel at atemperature of about 300 F. and activating the same at a temperature ofabout 1000 F. a product was produced having a Munsell color value ofabout 10.0 PBS/10. Upon exposing the so treated gel to an atmospherehaving a relative humidity of about 5% the color changed to about 10.0 14/3 M. C. V. and upon exposing the gel to an atmosphere having arelative humidity of about 10%, thecoloriurth'er changed to about 5.0 RP6/10 M. C. V.

SPEcnvni III-A exposing the so treated gel to an atmosphere 1 R; anindicator is obtained which is suitace oee 5.. having a relativehumidity on? about the color will change to aboutv 5.0 G 5/8 M; C. Uponexposing the gel to. an atmosphere having a relative humidity of aboutthe color will change to 10.0 G 5/6 M. C. V.

EXAMPLES SPECIMEN VIII-A If a copper. bromide impregnated gelcorresponding to that of. Example 7 and having a CuBrz content of.about. 4%. isv dried; at about 250 F. and activated. at a temperature ofabout 350 F., a product is obtained having a. Munsell color value ofabout 10.0 YB. 2/2. If this product isexposed to an atmosphere having arelative humidity of about the. colorwill' change to about 2.5 GY 4/4 M.C. V. If the. product is exposed to an atmosphere having a relativehumidity of about the color will change to about 2.5 G 6/6 M. c. v.

EXAMPLE 9 SPECIMEN IiV-A Cobalt bromide CoBrz is a suitable compound forassociation with a silica gel for the production of an indicator. Forinstance, by treating a silica gel such as described in Example 1 with asolution of cobalt bromide in a quantity and having a concentrationsuilicient to impregnate the gel to an extent of about A CoBrz, dryingthe product at a temperature of about 275 F. and activating at 400 F., aproduct is obtained having a Munsell color value of about 5.0 B 3/6.Upon exposing this product to an atmosphere having a relative humidityof about 5%, the color will change to about 7.5 B 7/2 M. C. V. Uponexposing the indicator to an atmospherehaving a relativehumidity ofabout 10%, the color will change to 7.5 R 8/4 M'. C. V.

' EXAMPLE 1o SPECIMEN VI-A By impregnating the silica gelof Example 1with a solution of cobalt bromide of such quantity and concentration asto impregnate. thegel to an extent of about 2% C'oBr2 and drying thesame at a temperature of about 200- F., a product is obtained having aMunsell color value of" .about 10.0 GY 3/4. Upon exposing this productEXAMPLE 11.

SPECIMEN VII-B By preparing anv indicator gel from silicagelcorresponding to that used in Example 1 andimpregnating the same with aquantity of cobalt. bromide to an extent of about 3%v and drying thesame at a temperature ofabout; 200,,F.,. a product is obtained having aMunsell color value of about 2.5 G 3/4. Upon exposing this product to anatmosphere having a relative. humidityof about.

10% thev color changed. to about 10.0:YR 5/8 M. C.

V. Upon exposing the product of this. example, to

an atmosphere having a relative humidity of:

about 20% the color changed to 2.5. YR 5 10.

. 6} EXAMPLE 12 SrEoIMEN IX-B' V A silica gel suchas that described inExample lwas impregnated with cobalt bromide to a content of about 2%COBI'z. Upon drying this product at a temperature of about 250 F;, aproduct was obtained having a Munsell color value-of about 7.5 YR'3/2.The color of this compound changed to abut 2.5 GY 6/4 M. C. V. uponexposing it toan atmosphere having a relative humidity of about 20%.When the product of this example was exposed to an atmosphere havingarelative humidity of about the color changed to about 7.5 G 7/6 M. C.V.

SPECIMEN V-A whereby the product has a C03(PO4)2 content of about /gdrying the product at about 250 F. and activating it. at a temperatureof about 400 R, an indicator gel was obtained having a Munsell colorvalue of about 7.5 PB 3/10. Upon exposing this product to an atmospherehaving a relative humidity of about 10% the color changed to about 5.0 R8/4 M. C. V. When the product was exposed to an atmosphere having arelative humidity of about 20% the color changed to about 2.5 R 8/4 M.C. V.

EXAMPLE l4 SPEC MEN V-B Cobalt chloride may be used invariousconcehtrations for association with silica gel for the production ofmoisture indicators in accordance with the present invention. Byincorporating cobalt chloride with a silica gel such as describedinconnection with Example 1 to such an. extent that the product has aCOC12 content of about, Ao drying the product at av temperature of about300 F. and activating it. at 400 F., an into an atmosphere having arelative humidity of about 20%.

' EXAMPLE 15 SPECIMEN VII-A about, 20% the color changed to about 10.0HP

EXAMPLE 1e I Specimen X-B at; treating a. silica. gel similar as that. a

Example 1 but which had been activated at a temperature of about 1100 F.with cobalt chloride in a quantity sufficient to have a C0012 content,drying the same at a temperature of about 300" F. and activating at atemperature of about 400? R, an indicator gel was obtained havingaMunsellcolor valueof about 7.5 PB 2/6. Upon exposing this product toanatmosphere having a relative humidity of about 40%, the. color changedto 10.0P 4/8 M. C. V. The same indi cater exposed to an atmospherehaving arelative humidity of about 60% exhibited a color of about 7.5 RP5/8 M. C. V.

EXAMPLE 17 SPECIMEN VI-B Copper chloride is another chromatic chemicalsuitable for use in accordance with the present invention. Byimpregnating silica gel prepared in accordance with that described inExample 1 with copper chloride to an extent whereby the resultingindicator gel has a CuClz content of about 2%, drying at a temperatureof about 300 F. and activating at a temperature of about 600 F., aproduct was obtained having a Munsell.

color value of about 7.5 GYe/fi. Upon exposing this indicator gel to anatmosphere having a relative humidity of about the color changed toabout 10.0 GY 7/8 M. C. V. and upon exposing the product toan'atmosphere having a relative humidity of about the color changed toabout 2.5 G 7/ 8 M. c. v.

EXAIVIPLE 18 SPECIMEN .VIII-B GY 5/2 M. C. V. When the same product wasexposed to an atmosphere having a relative humidity of about 30%, thecolor changed to about 10.0 PB '6/2 M. C. V.

EXAMPLE 19 SPECIMEN X- -A By heating a silica gel havinga cobalt iodidecontent of about 2% to a drying temperature of about 250 F., anindicator gel was obtained having a Munsell color value of about 7.5 GY2/2. This indicator gel changed its'color upon exposure to anatmosphere, having a relative humidity of about 40%, to about 2.5 Y. 6/6M. C. V. When this same indicator gel was exposed to an atmospherehaving a relative humidity of about the color changed to 2/5 YR 7/4 M.C. V. r v I EXAMPLE 2o SPECIMEN IX-A Bytreating a silica gel such asthat described in Example 1 with cobalt thiocyanate to produce anindicator gel having a CO(SCN)2 content of about and drying the same ata tempera-' ture of about 250- F., an indicator gel was obtained havinga Munsell color value of about an "atmosphere having a relative humidityof about 20%. Upon exposing the same compound to anatmosphere having arelative humidity of about 40% the color further'changed to about 7.5 RP6/8 M. C. V.

Many of the indicator gels. prepared according to the present inventionhave high adsorptive characteristics, especially those which areactivated after drying and these may beemployed for the same purposes asordinary desiccant silica gel as well as for moisture indicators. ofcourse, some of the indicator gels, especially those in which dryingwithout activation is employed to correlate the moisture content with'the other factors and characteristics, do not have the ad-. sorptivecapacity. of desiccantsilica gel. These indicator gels therefore areused principally for moisture indicating purposes. In some instancessuch indicator gels may be dispersed through masses'of desiccant silicagel having high adsorptive capacities to indicate When the desiccantsilica gel has taken up a predetermined quantity of moisture.

In impregnating the silica gel with the solution of chromatic chemical,the gel was first subjected to anatmosphere having a high relativehumidity to saturate thegei with moisture to such an extent that uponcontacting the same with a liquid the gel would not disintegrate, whichhappens upon contacting freshly activated gel with a liquid. Also bysaturating the gel to approximately 30% total volatile matter, onlyabout 50 ml. of solution isrequired to wet about 1 kilogram of gel. Asbefore indicated, the concentration of the solution of chromaticchemical is such that by wetting the saturated gel with the abovementioned quantity of solution per kilogram of gel, the desiredconcentration of chemical in the gel is obtained.

By holding the gel at the dryingtemperatures indicated in the precedingexamples, efiective drying is accomplished. Also by holdin the gel atthe activating temperaturesmentioned activation is effected. In eachinstance, the indicator gel was held at the drying and/or activatingtemperatures for about three hours.

- While the indicators have been described as including, carriers ofsilica gel impregnated with a chromatic chemical, it should beunderstood that other adsorbent carriersmay be used. For

instance, a porous adsorbent glass which is described in the Hood et a1.Patents Nos. 2,106,744, 2,315,328 and 2,315,329, maybe used as set forthin my copending application Serial No. 576,726, (now abandoned),filed-of even date herewith.

,To demonstrate the utility and practicability of the present invention,a specimen set of indicator gels was made and sealed in small glassampules. Each specimen consisted of three tubes or ampules, onecontaininga portion of a certain indicator gelbeiore exposure to anatmosphere, the relative humidity of which was to be determined, thesecond containing a portion of the same indicator gel after exposure toan atmosphere havin a predetermined relative humidity; and the thirdcontaining a portion of the same indicator gel after exposure to anatmosphere having a higher relative humidity. Apart from demonstratingthe color changes or breaks, these specimens are useful as standards forcomparisonof the colors of indicator gels exposed to atmospheres havingunknown relative um ie i. V V

Two 'sets of specimens were arranged. in framesior convenience inhandling and the frames were designated by Roman numerals and thespecimensin each frame were designated by the letters A andB;

v The following Tablel designates the constitution of the indicator gelsof the specimens and Table II designatesthe colors of the indicator gelsbefore and after. exposure to two atmospheres of diiferent relativehumidities, the humidities being'those at which the colors distinctlychange.

In the preceding examples and in Table II, colors .are described 'forthe indicator gels when exposed to two atmospheres of different relativehumidities. However, these two specific relative'humidities are to betaken as the upper and lower limits of a range in which a distinctivecolor break will occur, the color changing from that for the activatedindicator gel to a color within the range of colors, the limits of whichare indicated.

Data concerning the various specimens of indicator gels prepared inaccordance with the present invention are given in the following tables:

air having a certain relative humidity. The indicator gel ready for useis supported in any suitable manner for exposure to an atmosphere suchas air having an unknown relative humidity. One valuable use of theindicator gels is in connection with the maintenance of a moisture-freeatmosphere or an atmosphere the humidity of which is to be maintainedbelow'a predetermined maximum.

From the foregoing description, it will be appreciated that the presentinvention provides a moisture indicator, a method of making the same anda method of ascertaining the relative humidity of a gaseous atmosphere.Whil'e'reference has been made to a certain chromatic chemicals in thedescription of the indicator gels mentioned, these are given primarilyby way of example since other chromatic chemicals having colors varyingwith moisture content may be used.

I claim:

l. A method of preparing a quantitative relative humidity indicatorcomprising impregnating adsorbent silica selected from the groupconsisting of silica gel and porous glass with about /2 Table I INDEXT0.SPEOI1VIEN SET OF INDIOATING GELS Color Break (Rela- Indicator PerCent Activated Flame tive Humidity) on No. Gel 111mm Indicator Dned atat- F. F. I {.A. 214 85956-160 005.04 it B. %%P%- 85956-160 .....d 2 H i{.A. 1 3 85956-160 .-...d0--- 2 B. 85956-160 -.---d0 2 In {11. 85956-160CuBrz. '4 13. 85956-160 C0804. 2 Iv {A 85956-160 (301311. 54 B.129756-120 C0504. 3 v {A. 85956-160 (303(104) /a B. 85956-160 C00 56 VIA. 85956-160 CoBrz... 2 B. 85956-160 CuGlz. 2 VII {11. 85956-160...-.d0. 2 13. 85956-160 CoBrz. 3. 0 VIII {A. 85956-160 CuBrz 4 B.85956-160 C012 2 I: {A. 85956-160 Co(S B. 85956-160 CoBrz. 2 X A.85956-160 C012- 2 B. 11956-160 CoC12......--. 5

Table II APPROXIIMATE MUNSELL'GOLOR VALUEG%SO. V.) OF SPECIMEN SET OFINDICATING Frarn Relative 7 Relative Relative No. Humidity M HumidityHumidity M V I A. Activated... $4 7.5 10.0 RP 7/6. B. Activated.... RP6/10- A. Activated-.- 1 10.0 3 7.5 RP 7/6.

1 B. Activated... a 10.0 a 5.0 RP 6/10. In {11. Aetivated.... 5 5.0 G10.0 G 5/6.

B. Activated.... 5 7.5 R 10 10.0 RP 6/10. IV 1. Activated.... 5 7.5 B 107.5 R 8/4.

B ti t d 5 10. 10 5.0 6/10- V A. Aetivat xL 10 5.0 2.5 R 8/4. B.Activated. 10 7.5 20 7.5 RP 8/2. VI A. Activated. GY 10 5.0 20 2.5 YR7/6. {B. Activated- GY 4/ 10 10. 20 2.5 G 7/8. VH A. Activated. PB 107.5 20 10.0 RF 6/8. B. Activated.... G 3 10 10. 20 2.5 YR 5/10. VH7 A.Activated... 10.0 YB 20 2.5 2.5 G 6 6.

B. Activated... 7.5 PB 20 7.5 30 10.0 P 6/2. IX {1 1. Activated... 7.5PB 3/ 20 10. 7.5 RP 6/8.

B. Activated... 7.5 YR 20 2.5 40 7.5 G 7/6. c A. Activated... 7.5 GY 402.5 2.5 YR 7/4. B. Activated.-.. 7.5 PB 40 10. 60 7.5 HP 5/8.

In using the moisture indicator of the present invention, a gelimpregnated with a determined quantity of a selected chromatic chemicalis dried, or dried and activated, at predetermined temperatures toproduce an indicator having its characteristics, etc, correlated tochange color to 3%, on a dry basis, of cobalt sulphate, said cobaltsulphate having one color in a hydrated state and a different color in aless hydrated state, and heat treating the so impregnated silica at2501000 F., said indicator changing color when exposed to an atmospherehaving a relative huupon exposure to a gaseous atmosphere such as midityof 0-10%.

2. A quantitative relative humidity indicator as prepared by the methodof claim 1. r

3. A method of preparing a quantitative relative humidity indicatorcomprisingimpregnating activated silica gel without about /z%, on a drybasis, of cobalt sulphate, drying the impregnated silica gel at atemperature of about 250 F., and activating the impregnated silica gelat atemperature of about 525 F., said indicator changing color whenexposed to an atmosphere having a relative humidity of 4. A quantitativerelative humidity indicator consisting essentially of silica gelimpregnated with about /2%, on adry basis, of cobalt sulphate, saidindicator changing color when exposed to an atmosphere having a relativehumidity ranging from zero to ,41% and being prepared by the method ofclaim 3.

5. A method of preparing a quantitative relative humidity indicatorcomprising impregnating activated silica gel with about 2%, on a drybasis, of cobalt sulphate, drying the impregnated silica gel at atemperature of about 300 F.,'and activating the impregnated silica gelat a temperature of about 475, said indicator changing color whenexposed to an atmosphere having a rela tive humidity of A to /2 6. Aquantitative relative humidity indicator consisting essentially ofsilica gel impregnated with about 2%, on a dry basis, said indicatorchanging color when exposed to an atmosphere having a relative humidityranging from to and being prepared by the method of claim 5;

7. A method of preparing a quantitative relative humidity indicatorcomprising impregnating 1'2 activated silica gel with about 3%, on a drybasis, of cobalt sulphate, drying the impregnated silica gel at atemperature of about 300 F., and activating the impregnated silica gelat a temperature of about:1000 F., said indicator changing color whenexposed to an atmosphere having a relative humidity of 5-10%.

8. A quantitative relative humidity indicator consisting essentially ofsilica gel impregnated with about 8%, on a dry basis, of cobaltsulphate, said indicator changing color when exposed to an atmospherehaving a relative'humidity ranging from 5 to 10% and being prepared bythe method of claim 7.

. PAUL BELL DAVIS.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,947,381 Connolly et'al. Feb.13,1934 1,976,875 Connolly et a1 Oct. 16, 1934 2,210,862 Tronstad Aug.6, 1940 2,214,354 Snelling Sept. 10, 1940 FOREIGN PATENTS Number CountryDate 393,094 Great Britain June 1, 1933 280,934 Great Britain Feb. 18,1929 OTHER REFERENCES.

The Chemical Trade Journal and Chemical Engineer, July 14, 1939, page31.

Certificate of Correction Patent No. 2,460,065. January 25, 1949. PAULBELL DAVIS It is hereby certified that errors appear in the printedspecification of the above numbered patent requiring correction asfollows:

Column 7, line 7, example 16, for Munsell color value of about 7.5 PB2/6. read Munsell color value of about 7 .5 PB 2/8.; line 10, sameexample, for changed to 10.0 P 4/8 read changed to 10.0 P 4/6;

and that the said Letters Patent should be read With these correctionstherein that the same may conform to the record of the case in thePatent Office.

Signed and sealed this 31st day of May, A. D. 1949.

THOMAS F. MURPHY,

Assistant Commissioner of Patents.

